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Ann Thorac Surg 2008;85:460-464. doi:10.1016/j.athoracsur.2007.10.063
© 2008 The Society of Thoracic Surgeons
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Original Articles: Cardiovascular

Off-Pump Extraanatomic Aortic Bypass for the Treatment of Complex Aortic Coarctation and Hypoplastic Aortic Arch

Florian S. Schoenhoff, MDa, Pascal A. Berdat, MDa, Mladen Pavlovic, MDb, Alexander Kadner, MDa, Markus Schwerzmann, MDc, Jean-Pierre Pfammatter, MDb, Thierry P. Carrel, MDa,*

a Department of Cardiovascular Surgery, University of Berne, Berne, Switzerland
b Division of Pediatric Cardiology, University of Berne, Berne, Switzerland
c Department of Cardiology, University of Berne, Berne, Switzerland

Accepted for publication October 18, 2007.

* Address correspondence to Dr Carrel, Department of Cardiovascular Surgery, University Hospital Berne, Berne, Freiburgstrasse 3010, Switzerland (Email: thierry.carrel{at}insel.ch).


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Comment
 References
 
Background: Despite advances in surgical and interventional techniques, the optimal surgical treatment of severe aortic (re) coarctation and hypoplastic aortic arch is still controversial. Anatomic repair may require extensive dissection, cardiopulmonary bypass, and deep hypothermic circulatory arrest with their inherent risks. The aim of this study was to analyze the outcome of off-pump extraanatomic aortic bypass as a surgical alternative to local repair.

Methods: From February 2000 to December 2005, ten consecutive patients (median age 20 years; range, 11 to 38 years) with severe aortic (re) coarctation (n = 4) and (or) hypoplastic aortic arch (n = 7) underwent off-pump extraanatomic aortic bypass through median sternotomy. All but three patients had undergone previous surgery for coarctation and angioplasty or stenting. Three patients underwent concomitant replacement of the ascending aorta because of an aneurysm using cardiopulmonary bypass.

Results: Postoperative hospital course was uneventful in all patients. There was no perioperative mortality or significant morbidity. During a mean follow-up of 48 ± 22 months no patient required additional procedures. All patients were free of symptoms; no patient showed signs of heart failure after follow-up. At last follow-up, no patient presented with claudication, nor any patient experienced orthostatic problems due to a steal phenomenon. During follow-up, hypertension resolved in all patients with residual mild hypertension in two patients.

Conclusions: Off-pump extraanatomic aortic bypass is an attractive treatment option for complex aortic (re) coarctation and hypoplastic aortic arch. Perioperative risks are minimized, hypertension is influenced favorably, and midterm survival is event-free.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Comment
 References
 
Despite advances in surgical and interventional techniques severe (re) coarctation and hypoplastic aortic arch remains a challenging entity in congenital cardiac surgery. The optimal treatment strategy is still controversial. Anatomic repair may require extensive dissection, cardiopulmonary bypass (CPB), and deep hypothermic circulatory arrest, with their inherent risks [1].

In 1980, Vijayanagar and colleagues [2] published their concept of treating coarctation with an extraanatomic ascending-to-descending aortic bypass. In terms of nerve lesions and other complications associated with extensive dissecting, orthotopic ascending-to-descending aortic bypass seems superior to local repair in complex recoarctation. Unfortunately, orthotopic aortic bypass is prone to failure due to graft tension in the growing child. It is therefore associated with a risk of reoperation varying widely from 5% to 30%, depending on the study population.

The presence of a hypoplastic aortic arch has been identified as the major risk factor for reintervention [3]. After performing extraanatomic ascending-to-descending aortic bypass for several years with very satisfactory results, we evaluated the possibility of performing extraanatomic ascending-to-descending aortic bypass in patients with severe (re) coarctation and hypoplastic aortic arch using an off-pump approach. The aim of this study was to analyze the short and midterm outcomes of off-pump extraanatomic aortic bypass in a small series of patients with complex aortic (re) coarctation and hypoplastic aortic arch.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Comment
 References
 
From February 2000 to December 2005, ten consecutive patients (median age 20 years, range 11 to 38 years) with severe aortic (re) coarctation (n = 3) or hypoplastic aortic arch (n = 7) were included in the present series. Mean body weight was 59 kg (range, 40 to 85 kg), mean height 164 cm (range, 137 to 174 cm), mean body mass index 21.5 (range, 18 to 29), and mean body surface area 1.6 m2 (range, 1.4 to 1.9 m2). All patients underwent off-pump extraanatomic ascending-to-descending aortic bypass. Median graft size used was 16 mm (range, 12 to 19 mm). Three patients underwent additional replacement of the ascending aorta because of an isolated aneurysm of the ascending aorta without enlarged aortic root or aortic valve insufficiency using cardiopulmonary bypass. These three patients all had a bicuspid aortic valve. In one patient, a bypass had to be interposed between the ascending aorta and the left common carotid artery (CCA) with additional transposition of the left subclavian artery to the left common carotid to allow stent implantation to exclude a pseudoaneurysm at the site of previous repair.

Seven patients had undergone previous surgery at least once, mostly resection and end-to-end anastomosis, subclavian flap or patch aortoplasty, or interposition of a polyester tube graft. Two patients had a prior history of angioplasty and stenting. Reintervention in these patients became necessary due to a gradient of more than 30 mm Hg, upper limb hypertension, claudication, or renal insuffiency. Patients’ baseline characteristics are summarized in Table 1.


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  		Table 1 Baseline Characteristics of the Patients
 
In this series, eight patients presented with moderate to severe hypertension in rest, with excessively high blood pressure of more than 220 mm Hg systolic during excercise in four patients. Two patients showed only mild hypertension during rest and stress testing. Median blood pressure in rest was 150/90 mm Hg in our patient series despite antihypertensive medication with a combination therapy of up to four agents. Informed consent for publication was obtained during the initial hospitalization from all patients. Permission from the Institutional Review Board was obtained.

Surgical Technique
Surgery is performed through median sternotomy. After opening of the pericardium, the heart is gradually elevated using standard techniques from off-pump coronary surgery. The posterior pericardium is opened left to the vertebral column and the distal part of the descending aorta is exposed. After systemic heparinization (100 IU/kg) and tangential clamping of the descending aorta, an end-to-side anastomosis with a ring reinforced expanded polytetrafluoroethylene (ePTFE) graft (ImpraFLEX, Impra Inc., Tempe, Arizona) is performed. The graft is passed along the diaphragmatic aspect of the right ventricle, anterior to the inferior vena cava, around the right atrium and brought to the ascending aorta. Hemostasis at the distal anastomotic site is carefully controlled and the heart is then repositioned. After partial clamping of the ascending aorta the graft is anastomosed in the same way with a 4.0 polypropylene suture. After careful antegrade and retrograde removal of air, the procedure is finished in the usual fashion and heparin reversal is performed using 50% dosage of protamine sulfate. In patients who required replacement of the ascending aorta because of an aneurysm, the distal anastomosis is performed prior to cardiopulmonary bypass (Fig 1). Low-dose platelet antiaggregation therapy (Aspirin 100 mg/daily) is started on the first postoperative day and continued for at least one year.


Figure 1
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  		Fig 1. Intraoperative situs after replacement of the ascending aorta and extraanatomic aortic bypass in an 18-year old girl with ascending aneurysm combined with hypoplastic aortic arch and significant coarctation.

 

   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Comment
 References
 
There was no mortality, nor significant morbidity. The intraoperative and postoperative hospital course was uneventful in all patients. Mean aortic cross-clamp time was 43 minutes, mean cardiopulmonary bypass time was 60 minutes when CPB was necessary (n = 3). Cardiopulmonary bypass was performed in mild hypothermia of 32°C; no deep hypothermic circulatory arrest had to be performed. Mean intensive care unit stay was less than one day; mean hospital stay was eight days. One patient developed uncomplicated pneumonia which resolved after antibiotic treatment. Antihypertensive treatment, preferentially with a betablocker, was followed for two months postoperatively and then reduced according to blood pressure at rest and during exercise, after Joint National Committee/American Heart Association guidelines for the treatment of hypertension [4].

Follow-up is complete and was performed at 3, 6, and 12 months postoperatively, and then individually, but at least once a year, using two-dimensional echocardiography, magnetic resonance imaging, or computed tomographic scanning (Figs 2; 3). Hypertension resolved in all patients during follow-up with residual mild hypertension in two patients. Antihypertensive treatment with betablockers in moderate dosage was performed in three patients and one patient is receiving a combination therapy of a betablocker and a calcium-channel blocker.


Figure 2
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  		Fig 2. Postoperative magnetic resonance-angiography after extraanatomic ascending-to-descending aortic bypass.

 

Figure 3
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  		Fig 3. Three-dimensional volume images of extraanatomic aortic bypass in a 31-year-old woman (A) with multiple previous interventions, including resection and patch angioplasty, percutaneous dilatation, redo-surgery due to recoarctation, and finally Wallstent (Schneider [USA] Inc, Minneapolis, MN), implantation (B) to exclude a pseudoaneurysm. Extraanatomic bypass was necessary to restore adequate perfusion of the lower extremities and was associated with transposition of the left subclavian artery into the left common carotid artery which was connected to the ascending aorta using an 8-mm Dacron graft (Boston Scientific Corp, Natick, MA).

 
Median reduction in systolic blood pressure after a median time of 24 months was 40 mm Hg (range, 0 to 80 mm Hg) and median reduction in diastolic blood pressure was 10 mm Hg (range, 0 to 20 mm Hg) (Table 2). During a mean follow-up period of 48 ± 22 months, no patient needed reintervention. There was no pathological finding on any of the anastomosis, and especially there was no case of pseudoaneurysm formation. All patients were free of symptoms and no patients showed signs of heart failure after follow-up. At last follow-up, no patient presented with claudication, nor did any patient experience orthostatic problems due to a steal phenomenon.


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  		Table 2 Preoperative and Postoperative Blood Pressure Measurements
 

   Comment
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
References
 
According to the literature, primary surgical repair of aortic coarctation may result in recoarctation in 5% to 30% of the cases, varying according to the initial presentation, the technique used, and the presence of a hypoplasia of the distal aortic arch [5]. The presence of a hypoplastic aortic arch has been identified as one of the most important risk factors for reintervention in patients with coarctation. One reason may be underdiagnosed hypoplasia of the aortic arch and consecutive less aggressive treatment.

When extraanatomic ascending-to-descending aortic bypass was introduced by Vijayanagar and colleagues in 1980 [2] it was described as an attractive option in patients with concomitant cardiac disease requiring additional surgery. In these cases, the procedure was performed through median sternotomy, thus avoiding lateral thoracotomy to correct coarctation. In the current era, this approach has turned out to be an excellent alternative for complex redo cases and for situations in which the surgeon would like to avoid in situ repair and cardiopulmonary bypass. In fact, the extraanatomic approach avoids nearly all intraoperative risks associated with extracorporeal circulation and deep hypothermia. Previous reports on ascending-to-descending extraanatomic aortic bypass showed a perioperative mortality as high as 7% to 17% [6]. Our own contemporary experience reveals that significant progress has been accomplished because we did not observe any case of perioperative mortality, nor any death during the midterm follow-up.

Preoperative arterial hypertension was influenced favorably by surgery. In the present series we are able to demonstrate that ascending-to-descending aortic bypass is a valuable option to normalize blood pressure (at rest and during exercise), even in patients with long-standing hypertension.

An important technical issue of extraanatomic ascending-to-descending aortic bypass is the selection of an adequate size of the prosthetic graft. We choose the size of the graft according to the diameter of the descending aorta (1:1 or slightly less). We prefer to use ring reinforced ePTFE grafts rather than Dacron grafts to avoid compression by adjacent structures and late dilation of the graft [7]. In contrast to other series, we do not pass the graft posterior, but anterior to the inferior vena cava (IVC), because we believe this will avoid compression of the pulmonary veins and the IVC [8].

We consider extraanatomic aortic bypass an attractive alternative to local repair in cases of complex (re) coarctation and in patients with a long hypoplastic aortic arch segment. In situ anatomic repair requires extracorporeal circulation using hypothermic circulatory arrest and cerebral protection and is associated with a risk of paraplegia of about 3% to 5% [9, 10]. A recent publication by McKellar and colleagues [11] showed excellent medium- to long-term results in the setting of extraanatomic aortic bypass using extracorporeal circulation in a large group of 50 patients, in whom five patients (10%) needed deep hypothermic circulatory arrest. Despite low overall perioperative morbidity, 10% of the patients needed reexploration for bleeding. One patient experienced right lower-extremity weakness. We think complications with this technique, like the ones mentioned above, can be further reduced by using an off-pump approach. Off-pump ascending-to-descending aortic bypass preserves a physiological perfusion during the procedure. Furthermore it may reduce the risk of spinal injury because spinal blood supply through the upper intercostal arteries is preserved. Moreover, the off-pump extraanatomic bypass is an expeditious procedure which rarely needs more than two hours.

Major limitations of ascending-to-descending aortic bypass are the age of the patient and the size of the aorta. We believe that this approach is not indicated in children and infants but should be discussed in adolescents and younger adults. In the neonate and infant local repair, for example, extended end-to-end resection remains the therapeutic strategy of choice and can be performed with satisfactory results as already shown by other groups [12, 13]. When there is doubt about somatic growth of the patient, the right pleural space can be opened to gain enough space to implant a graft long enough for an adult patient.

In conclusion, off-pump extraanatomic aortic bypass is an attractive and efficient surgical strategy for complex aortic (re) coarctation and hypoplastic aortic arch, especially in patients with additional cardiac disease and in those with multiple prior interventions. This approach allows to minimize the perioperative risks, and to avoid cardiopulmonary bypass, thoracotomy, and surgical dissection in a preoperated area. This approach offers an excellent early and midterm outcome.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 References
 

  1. Ralph-Edwards AC, Williams WG, Coles JC, Rebeyka IM, Trusler GA, Freedom RM. Reoperation for recurrent aortic coarctation Ann Thorac Surg 1995;60:1303-1307.[Abstract/Free Full Text]
  2. Vijayanagar R, Natarajan P, Eckstein PF, Bognolo DA, Toole JC. Aortic valvular insufficiency and postductal aortic coarctation in the adultCombined surgical management through median sternotomy: a new surgical approach. J Thorac Cardiovasc Surg 1980;79:266-268.[Abstract]
  3. Dodge-Khatami A, Backer CL, Mavroudis C. Risk factors for recoarctation and results of reoperation: a 40-year review J Card Surg 2000;15:369-377.[Medline]
  4. Chobanian AV, Bakris GL, Black HR, et al. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure Hypertension 2003;42:1206-1252.[Abstract/Free Full Text]
  5. Amato JJ, Douglas WI, James T, Desai U. Coarctation of the aorta Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2000;3:125-141.[Medline]
  6. Heinemann M, Ziemer G, Wahlers T, Koehler H, Borst H. Extraanatomic thoracic aortic bypass grafts: indications, techniques, and results Eur J Cardiothoracic Surg 1997;11:169-175.[Abstract/Free Full Text]
  7. Halstead JC, Meier M, Etz C, et al. The fate of the distal aorta after repair of acute type A aortic dissection J Thorac Cardiovasc Surg 2007;133:127-135.[Abstract/Free Full Text]
  8. Connolly HM, Schaff HV, Izhar U, Dearani JA, Warnes CA, Orszulak TA. Posterior pericardial ascending-to-descending aortic bypass: an alternative surgical approach for complex coarctation of the aorta Circulation 2001;18:133-137.
  9. Almeida de Oliveira S, Lisboa LA, Dallan LA, Abreu FCA, Rochitte CE, de Souza JM. Extraanatomic aortic bypass for repair of aortic arch coarctation via sternotomy: midterm clinical and magnetic resonance imaging results Ann Thorac Surg 2003;76:1962-1966.[Abstract/Free Full Text]
  10. Barron DJ, Lamb RK, Ogilvie BC, Monro JL. Technique for extraanatomic bypass in complex aortic coarctation Ann Thorac Surg 1996;61:241-244.[Abstract/Free Full Text]
  11. McKellar SH, Schaff HV, Dearani JA, et al. Intermediate-term results of ascending-descending posterior pericardial bypass of complex aortic coarctation J Thorac Cardiovasc Surg 2007;133:1504-1509.[Abstract/Free Full Text]
  12. Wright GE, Nowak CA, Goldberg CS, Ohye RG, Bove EL, Rocchini AP. Extended resection and end-to-end anastomosis for aortic coarctation in infants: results of a tailored surgical approach Ann Thorac Surg 2005;80:1453-1459.[Abstract/Free Full Text]
  13. Kadner A, Dave H, Bettex D, Valsangiacomo-Buechel E, Turina MI, Pretre R. Anatomic reconstruction of recurrent aortic arch obstruction in children Eur J Cardiothorac Surg 2004;26:60-65.[Abstract/Free Full Text]

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